JP3944992B2 - Playback apparatus and playback method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital audio reproducing apparatus and a reproducing method, such as a CD player for reproducing a CD (compact disc) and an MD recorder having a function for reproducing an MD (mini disc).
[0002]
[Prior art]
In a digital audio playback apparatus, reverse playback is possible by playing back each sampling data in digital audio data generated based on a playback signal played back from a recording medium in the reverse order of the time sequence of actual performance. This is well known.
[0003]
For example, even in an MD recorder, reverse reproduction is possible by performing arrangement conversion processing on digital audio data and arranging individual sampling data in the reverse order of the actual performance over time. However, in an actual MD recorder, the generated digital audio data is output to the subsequent stage in units of data blocks as an aggregate of a predetermined number of sampling data (see FIG. 5).
[0004]
Therefore, only reverse order output in units of data blocks is possible. Such reproduction is hereinafter referred to as pseudo reverse reproduction. In the pseudo reverse reproduction, the sampling data array is arranged in the actual performance time order in each data block. Accordingly, discontinuity occurs in the sampling data at the boundary between a certain data block M and the succeeding data block M-1.
[0005]
For this reason, the reproduction sound of the pseudo reverse reproduction becomes unnatural compared to the reproduction sound originally generated by reverse reproduction, that is, by arranging individual sampling data in the reverse order to the actual performance time passage. There is. In order to cope with this problem, a configuration circuit having a function of converting the data array in each data block in the reverse order is provided. As such a configuration, for example, a general-purpose DSP (Digital Signaling Processor) capable of memory control can be used.
[0006]
However, in such a configuration, a counter for counting the number of sampling data corresponding to the block length of the data block, a storage area for storing a memory address storing the sampling data at the head of each data block, and the like are managed. There is a need to. This complicates the processing for memory management and causes problems such as an increase in program capacity and a decrease in processing speed.
[0007]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a playback apparatus and playback method capable of performing high-precision reverse playback without increasing the program capacity, lowering the processing speed, or minimizing the extent thereof. It is to provide.
[0008]
[Means for Solving the Problems]
The invention of claim 1, compressed audio data in the playback device you reading and reproducing audio data from a recording medium recorded in blocks,
Reproduction means for reading out audio data compressed from the recording medium in units of blocks; decompression means for performing decompression processing of compressed audio data in units of blocks read by the reproduction means;
Of the timing data is output from the decompression unit, the block header data timing signal generating means for generating and outputting a block top data timing signal indicating that there at the beginning of a data block unit,
Ring buffer means for temporarily storing data output from the decompression means ;
When audio data compressed in reverse order in block units from the recording medium is played back by the playback means, during normal playback to the ring buffer means based on the block head data timing signal output from the block head data timing signal generation means a data sequence variable 換手 stage for converting an array of data to be stored in reverse order to the,
A write position control means for moving the write position in the direction opposite to the reading direction of the data from the ring buffer when storing the data in the ring buffer means in the reverse order to that during normal reproduction;
Is a playback device.
[0009]
According to another aspect of the invention, compressed audio data in the playback how to reading and reproducing audio data from a recording medium recorded in blocks,
Reading audio data compressed in the reverse order from the normal playback in block units from the recording medium;
Decompressing compressed audio data read in block order in reverse order;
Generating a block head data timing signal indicating the head data of the decompressed block unit data ;
When the playback order opposite to the normal playback order is instructed, the storage position of the decompressed audio data in the ring buffer memory for temporarily storing the decompressed audio data is reversed to the normal playback order. Generating storage location information in
When the playback order opposite to the normal playback order is specified, each time the block head data timing signal is detected, the audio data decompressed in block units in the reverse order to the normal playback is stored in the ring buffer memory. Memorizing based on information and
Is a playback method.
[0010]
According to the above invention, at the time of reverse reproduction, the data array conversion process can be accurately performed based only on the output timing of the sampling data at the head of the data block ascertained from the block head data timing signal. Then, it is possible to realize high-accuracy reverse reproduction that does not have discontinuities in units of sampling data.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The overall configuration of one embodiment of the present invention will be described below with reference to FIG. The audio data generation unit 21 performs processing such as decoding, error correction, and ATRAC (Adaptive TRansform Acoustic Coding) decompression based on a reproduction signal reproduced from a recording medium such as an MD, and decompresses ATRAC as reproduction digital audio data. Data is generated and output to the subsequent stage. This ATRAC decompressed data is in units of data blocks made up of a predetermined number of sampling data. In addition, the audio data generation unit 21 outputs a block head data output timing signal indicating the output timing of data at the head of each data block to the subsequent stage. Furthermore, the audio data generation unit 21 has a function of performing pseudo reverse reproduction output of ATRAC decompressed data.
[0012]
ATRAC is a compression method of digital audio data that has been used relatively recently in MD, and is a combination of modified DCT (Modified Discrete Cosine Transfer) and processing that takes into account human auditory characteristics. is there. In one embodiment of the present invention, the compression rate by ATRAC is about four times. That is, when the ATRAC decompression process is performed on the decoded data based on the reproduction signal reproduced from the recording medium, the ATRAC decompressed data having a data amount about four times the decoded data is obtained.
[0013]
The recorded digital audio data before compression has a dynamic range, that is, the amount of information per sample is 16 bits = 2 bytes. 512 samples (and thus 512 × 2 = 1024 bytes) are compressed to 212 bytes by ATRAC. These 212 bytes are referred to as one sound group. Furthermore, 5.5 sound groups constitute one sector, and 32 sectors constitute one cluster.
[0014]
One sector (that is, 1024 × 5.5 = 5632 bytes after ATRAC decompression) is the minimum unit of data output from the audio data generation unit 21 in the MD recorder. Accordingly, in the MD recorder, one data block corresponds to one sector. In a CD player, one data block is one frame (consisting of 588 channel bit data, which corresponds to 1/75 second reproduced audio data).
[0015]
A storage circuit 23 provided with a data array conversion control unit 22 and a ring buffer 24 made of, for example, a RAM (which will be described later) is provided at the subsequent stage of the audio data generation unit 21. When the reverse reproduction mode is instructed, the audio data generation unit 21 performs pseudo reverse reproduction output, and controls the storage circuit 23 with reference to the audio data generation unit 21 block head data output timing signal. Thus, the sampling data in each data block is rearranged in the reverse order and output. In one embodiment of the present invention, a RAM or the like used as a buffer memory for the shock proof memory function is provided in the storage circuit 23 separately from the ring buffer 24.
[0016]
The shock proof memory function interrupts the playback sound when the playback signal from the recording medium is interrupted when the signal reading unit such as an optical pickup shifts from the correct reading position due to vibration applied to the device (so-called sound skipping). ) To prevent or reduce the possibility. In order to realize this function, a buffer memory such as a RAM is provided, a digital audio data supplied from the audio data generation unit 21 is temporarily stored in the buffer memory, and then a subsequent processing circuit for performing D / A conversion or the like The configuration as supplied to is used.
[0017]
With such a configuration, even if the reproduction signal from the recording medium is interrupted and the generation of new digital audio data is interrupted, reproduced sound is generated based on the data stored in the buffer memory. Therefore, there is no interruption in the reproduced sound until there is no data in the buffer memory. During this time, if the signal reading means such as an optical pickup is returned to the correct reading position and the reproduction signal is returned to the normal reading state, the occurrence of sound skipping can be prevented.
[0018]
When the reverse playback mode is instructed, the audio data generation unit 21 performs pseudo reverse playback output, and stores as described below with reference to the audio data generation unit 21 block head data output timing signal. By controlling the circuit 23, the sampling data in each data block is rearranged in the reverse order and output. The ring buffer memory 24 in the memory circuit 23 will be described with reference to FIG. The ring buffer memory 24 has a capacity capable of storing a data amount that is twice the data amount of the data block. The data array conversion control unit 22 controls the ring buffer memory 24, that is, sets a write point and a read point.
[0019]
The control of the write point is as follows. First, the writing point of the sampling data at the head of the data block is set. Thereafter, the subsequent sampling data is sequentially written by updating the writing point in a certain direction. On the other hand, as will be described later, the reading point is controlled so that the update direction differs between normal playback and reverse playback.
[0020]
At the time of normal reproduction, the reading point 26 from the ring buffer memory 24 is set on the writing point 27 of the latest sampling data or on the writing point of the sampling data written several points before the latest data. That is, the update direction of the read point is the same as the update direction of the write point. In this way, the sampling data is read in the order of the writing points and output to the subsequent stage.
[0021]
Next, processing at the time of reverse reproduction will be specifically described with reference to FIG. Here, FIG. 3A illustrates the setting of the write point and the read point for the ring buffer memory 24. FIG. 3B illustrates the output of the audio data generation unit 21 in the reverse playback mode. Further, FIGS. 3C and 3D respectively show the writing of data blocks to two areas P and Q on the ring buffer memory 24 described later. On the other hand, FIG. 3E shows the data after array conversion read from the ring buffer memory 24.
[0022]
As described above, in the reverse playback mode, the audio data generation unit 21 performs pseudo reverse playback output, so that ATRAC decompressed data is in the order of data blocks M, M-1, M-2,... As shown in FIG. Is output and supplied to the ring buffer 24. Here, in each data block, the sampling data is arranged as 1, 2,..., N in the order of sampling.
[0023]
If the internal arrangement of each data block remains in the sampled order, for example, the data immediately before the last (ie, nth) sampled data in the data block M is output. The top sampling data of the block M-1 is output. Therefore, discontinuity occurs in the sampling data unit to be output at the boundary of the data block. When the subsequent processing is performed based on such output, sound data that is unnaturally generated is generated.
[0024]
Thus, in one embodiment of the present invention, as shown in FIG. 3A, the read point update direction is opposite to the write point update direction during reverse playback. For example, when the reverse reproduction mode starting from the data block M is instructed, a write point for writing the first (that is, the first) sampling data in the data block M (symbol S is added in FIG. 3A). The update direction of the read point (shown with an arrow 51) is set in a direction opposite to the update direction of the write point (shown with an arrow 50).
[0025]
By such control on the ring buffer 24, the sampling data in the data block M is written in the order of 1, 2,... N in the area P indicated by hatching in the period a in which the data block M is written. It will be rare. Here, the region P occupies half of the ring buffer 24. As described above, since the capacity of the ring buffer 24 is twice the data capacity of the data block, the data block M can be written onto the area P without excess or deficiency.
[0026]
In the period a, reading is performed from the area Q on the ring buffer 24 other than the area P (therefore, the area Q also has a data capacity for one data block). However, the data read out during the period a is, for example, data that was written when normal playback was performed before the time point when the reverse playback mode was commanded, and the reverse playback output required here is It is unrelated. Therefore, the data read in period a is not output to the subsequent stage (see FIG. 3E).
[0027]
At the end of the period a, that is, when the writing of the data block M is completed, the writing point is located at the point T opposite to the point S. At this time, the reading point is located at point T. Therefore, the data block M-1 supplied by the pseudo reverse reproduction output by the audio data generation unit 21 is continuously written in the region Q in the order of 1, 2,... N (see FIG. 3D).
[0028]
In this way, in the period in which data block M-1 is written (period b in FIG. 3), data block M written in period a is read from region P. At this time, the sampling data in the data block M is read in the order of n, n−1,..., 2 in the opposite order of writing (see FIG. 3E). In this way, the output order of the sampling data in the data block M can be reversed from the sampling order.
[0029]
Furthermore, at the end of the period b, that is, when the writing of the data block M-1 is completed, the writing point is located at the point S. At this time, the reading point is located at point T. That is, the state is the same as when the writing of the data block M is started. Subsequently, the data block M-2 supplied by the pseudo reverse reproduction output by the audio data generation unit 21 is written in the area P in the order of 1, 2,... N (see FIG. 3C).
[0030]
In this way, in the period in which data block M-2 is written (period c in FIG. 3), data block M-1 written in period b is read from region Q. At this time, the sampling data in the data block M-1 is read in the order of n, n-1,..., 2, 1 in the opposite order of writing (see FIG. 3E). In this way, the output order of the sampling data in the data block M-1 can be reversed from the sampling order.
[0031]
Similarly, the data blocks supplied by the pseudo reverse reproduction output by the audio data generation unit 21 are sequentially written in and read out from the ring buffer 24, whereby the sampling order of all sampling data (accordingly, accordingly). It is possible to output in reverse order of the time sequence of actual performance).
[0032]
Hereinafter, as a more specific configuration example, an MD recorder to which the present invention is applied will be described with reference to FIG. Here, the data read block 11 and the ATRAC decompression block 12 are included in the audio data generation unit 21 in FIG. However, the block head data timing signal Bf is generated by the control microcomputer 14 as will be described later. The data array conversion block 13 includes a data circuit conversion control unit 22 and a storage circuit 23 having a ring buffer 24 in FIG.
[0033]
Data reproduced from the MD 10 by the data read block 11 is supplied to the ATRAC decompression block 12. The ATRAC decompression block 12 performs ATRAC decompression processing on the supplied data, generates ATRAC decompression data, and supplies it to the data array conversion block 13. The data read block 11 and the ATRAC decompression block 12 can perform both 1 × speed reproduction and 2 × speed reproduction.
[0034]
The control microcomputer 14 that controls the operation of the entire apparatus generates a block head data timing signal Bf according to the data processing status in the data read block 11 and the ATRAC decompression block 12, and uses the block head data timing signal Bf as data. This is supplied to the array conversion block 13. The data transfer rate of the ATRAC decompressed data is fixed at a rate corresponding to, for example, 88.2 kHz, which is twice 44.1 kHz, according to a data transfer clock generated by a PLL circuit (not shown) or the like.
[0035]
The data array conversion block 13 performs processing for the shock proof function, and at the time of reverse reproduction, the order of the samples in each data block of the ATRAC decompressed data supplied with reference to the block head data timing signal Bf. Convert. As a result, the sample order is continued even at the boundary of the data block during reverse reproduction.
[0036]
The output of the data array conversion block 13 is supplied to the D / A conversion block 14. The D / A conversion block 14 D / A converts the supplied digital audio data to convert it into an analog signal. A sound generator such as a headphone speaker is driven by the analog signal, and sound is output.
[0037]
In the above-described embodiment of the present invention, the ring buffer 24 used for performing data array conversion, the RAM used as a buffer memory for performing the shock proof memory function, and the like are provided separately. A single rewritable memory is provided in the memory circuit 23. During normal playback, this memory is used exclusively as a buffer memory for performing the shockproof memory function, and during reverse playback, a part of the memory operates as a ring buffer 24. You may make it let it. In such a configuration, control over the memory in the memory circuit 23 is complicated, but the total amount of memory in the memory circuit 23 can be reduced.
[0038]
The present invention is applied to the MD recorder, which is an embodiment of the present invention described above. The present invention outputs data reproduced in the reverse order of the sampling order in units of a predetermined amount of data such as data blocks. If the playback apparatus has a playback processing system having a function, the present invention can also be applied to the case where a recording medium, a communication line, or the like is used as a configuration for supplying data to be played back to the playback system.
[0039]
That is, in addition to the MD, for example, a rewritable disk such as a magneto-optical disk (MO), a phase change disk PD, a CD-E (CD-Erasable), a write-once disk such as a CD-R, a CD, a CD-ROM, The present invention can be applied to a read-only disk such as a DVD or the like and a digital sound reproducing apparatus using a magnetic disk. Furthermore, the present invention can be applied to a tape-shaped recording medium such as a magnetic tape or an optical tape, or a semiconductor memory as a recording medium. Also, the present invention can be applied to a case where data to be reproduced from a content server or the like is supplied to a reproduction system via a network using a telephone line or the like, for example.
[0040]
In particular, devices that use digital devices to achieve the same or similar functions as analog devices, devices that have a function to search editing points using a jog dial, etc., require low-cost, high-quality reverse playback functions It is effective to apply the present invention to a device to be used. In addition, in general signal processing including reproduction of video data, for example, it is effective to apply the present invention in order to realize a function of rearranging and outputting a data string in a specific range in reverse.
[0041]
Further, the present invention is not limited to the above-described embodiment, and various applications and modifications can be considered without departing from the gist of the present invention.
[0042]
【The invention's effect】
As described above, according to the present invention, in a playback apparatus that plays back digital audio information from a recording medium, pseudo reverse playback output is performed with a predetermined amount of data such as a data block as an output unit. By performing processing using a ring buffer having a memory capacity twice that of the data block with reference to the block head data timing signal indicating the output timing of the head of the data block with respect to the reverse reproduction output, Data array conversion processing for converting the order of sampling data is performed.
[0043]
With such a configuration, at the time of reverse reproduction, when the sampling data for a certain data block M is read out in the reverse order from the half area of the ring buffer, the subsequent data block M-1 becomes the other half of the ring buffer. It is made to be written in the area. Therefore, after the data block M is read in the reverse order, the data block M-1 can be read in the reverse order immediately. For this reason, it is possible to realize high-accuracy reverse reproduction without discontinuity in units of sampling data without performing special processing such as read point / write point jump processing.
[0044]
Therefore, the data array conversion process can be appropriately performed based only on the output timing of the sampling data at the head of the data block ascertained from the block head data timing signal. For this reason, for example, it is necessary to perform a process of counting the number of sampling data, a process of storing the storage address of the sampling data at the head of the block, and the like performed in a conventional data array conversion process using a DSP or the like. It can be lost.
[0045]
Therefore, the data array conversion process can be simplified, and the program capacity and processing time for performing the data array conversion process can be reduced. Therefore, it is possible to contribute to downsizing and cost reduction of the overall configuration of the apparatus.
[Brief description of the drawings]
FIG. 1 is a block diagram for explaining an overall configuration of an embodiment of the present invention.
FIG. 2 is a schematic diagram for illustrating a ring buffer according to an embodiment of the present invention.
FIG. 3 is a schematic diagram for explaining a data array conversion process;
FIG. 4 is a block diagram for explaining an example of a more specific configuration of an embodiment of the present invention.
FIG. 5 is a schematic diagram for explaining a data block and a sampling block in the output of digital audio data.
[Explanation of symbols]
21 ... Audio data generation unit, 23 ... Data array conversion control unit, 23 ... Storage circuit, 24 ... Ring buffer

Claims (2)

In playback apparatus compressed audio data reading and reproducing audio data from a recording medium recorded in blocks,
Reproducing means for reading audio data compressed from the recording medium in blocks, and decompression means for performing a decompression process of the compressed audio data in block units that is read by the reproducing means,
Of the timing data from said decompression means is output, and the block head data timing signal generating means for generating and outputting a block top data timing signal indicating that there at the beginning of the data of the block unit,
Ring buffer means for temporarily storing data output from the decompression means ;
The ring buffer means based on the block head data timing signal output from the block head data timing signal generation means when the reproducing means reproduces the audio data compressed in reverse order in block units from the recording medium. a data sequence variable 換手 stage for converting an array of data to the normal reproduction is stored in reverse order to,
A write position control means for moving the write position in the direction opposite to the reading direction of the data from the ring buffer when storing the data in the ring buffer means in the reverse order to the normal reproduction;
A playback device comprising: In playback method compressed audio data you reading and reproducing audio data from a recording medium recorded in blocks,
A step of the normal reproduction reads the audio data compressed in the reverse order in block units from the recording medium,
Decompressing the compressed audio data read in block units in the reverse order;
Generating a block head data timing signal indicating the head data of the decompressed block unit data ;
When a playback order opposite to the normal playback order is instructed, the storage position of the decompressed audio data is stored in the reverse order to the normal playback in the ring buffer memory for temporarily storing the decompressed audio data. Generating memory location information so that
When the playback order opposite to the normal playback order is specified, every time the block head data timing signal is detected, the audio data decompressed in the block unit in the reverse order to the normal playback in the ring buffer memory. Storing based on the storage position information;
A playback method comprising:

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